Hide nav menu items from bp group

I’m pretty new to WordPress. I’m working on a multisite network and trying to hide an item in the nav menu from users who aren’t in a certain bp group. I tried using a plugin that says it allows the use of WP conditional tags to disable menu items (http://wordpress.org/extend/plugins/menu-items-visibility-control/) with a billion different variations on:

bp_group_is_member(‘2’)

But it doesn’t seem to work – I’m guessing bp_group_is_member isn’t a WP conditional tag, and that’s why?

If anyone could suggest another way to do this, or let me know if there’s something different I should be doing with this plugin, that would be great.